Question :
What is a better solution to host a flask application on AWS ? ECS or EKS or Fargate ?

Looking for personal experiences and opinions

To answer that, a little more information is needed.

If you can, Amplify or Lambda would be my first choices. But obviously it depends on your requirements etc

Go with digital ocean deploy, seems more cheaper and less complicated option than what you mentioned.

2 second summary - EKS is more standardised and gives you more control, ECS is proprietary and not as fully featured but simpler to set up and cheaper to run. We've generally gone with ECS because it's cheaper, but that's about it.

Fargate isn't comparable - it's more like Fargate Vs EC2. In that case we go for Fargate pretty much every time, as it means we don't need to maintain the underlying instances.